1. Field of the Invention
The present invention relates to a method of fabricating a liquid crystal display panel, and more particularly, to a method of manually sealing a liquid crystal injection inlet of a liquid crystal display panel.
2. Discussion of the Related Art
Lately, a liquid crystal display device highlighted as a flat panel display exhibits a high contrast ratio, is suitable for displaying gray scales or moving pictures, and requires less power consumption. However, efforts are continually being made to research and develop the liquid crystal display device.
The liquid crystal display device includes a liquid crystal display panel constituted with TFT(thin film transistor) and color filter substrates confronting each other and a liquid crystal layer formed between the two substrates. A method of fabricating a liquid crystal display panel according to related art is explained by referring to the attached drawings as follows.
FIG. 1 illustrates a flowchart of a method of fabricating a liquid crystal display panel according to a related art, and FIG. 2 schematically illustrates a method of manually sealing a liquid crystal injection inlet according to related art.
Referring to FIG. 1, first and second substrates are prepared (S10) as follows:
The first substrate is prepared by successively forming a black matrix on a transparent substrate so as to prevent light leakage, a color filter layer of red, green, and blue between the black matrix, and a common electrode on the entire surface including the color filter layer by deposition of ITO (indium tin oxide).
The second substrate is prepared by successively forming a plurality of gate and data lines on the other transparent substrate so as to cross with each other, a thin film transistor on each intersection between the gate and data lines so as to consist of a gate electrode, a gate insulating layer, a semiconductor layer, and source/drain electrodes, and a pixel electrode made of ITO to be connected electrically to the drain electrode of the thin film transistor.
Subsequently, a spacer is scattered evenly on the first substrate so as to maintain a uniform cell gap. A sealant is printed thick on the second substrate so as to leave a portion (hereinafter called liquid crystal injection inlet) of the second substrate for injecting liquid crystals (S11).
After the two substrates have been attached to each other so as to confront each other, hot pressure is applied to the attached substrates to harden the sealant and completely bond the two substrates to each other (S12).
After a vacuum state has been achieved inside the bonded substrates, liquid crystals are injected inside the bonded substrates through the liquid crystal injection inlet using capillary action and atmospheric pressure differences. The liquid crystal injection inlet is then sealed under a pressurization state so as to prevent the liquid crystals from completely leaking to the outside (S13).
In this case, the liquid crystal injection inlet is sealed automatically by 1CST (cassette) unit. Namely, after a number of liquid crystal display panels (usually, 60 panels) have been loaded simultaneously on a cassette, a sealing material is coated on the liquid crystal injection inlets using an automated machine.
If the automated machine experiences some difficulty so as to be unable to perform the automatic sealing step, as shown in FIG. 2, a worker manually coats the liquid crystal injection inlet of the liquid crystal panel 3 with a sealing material, one-by-one, using a sealing apparatus 1.
The sealing apparatus 1 functions like a syringe. A predetermined amount of the sealing material 4 sticks to an end of the syringe to be coated on the liquid crystal injection inlet 2 of the liquid crystal display panel 3.
The automatically or manually coated sealing material is then heated or irradiated with UV-rays to a hardened state. Thus, the liquid crystal injection inlet becomes completely sealed or airtight.
After a cleaning process has been carried out using ultrasonic waves so as to remove particles and the like adhering to an outer surface of the LC-injected liquid crystal display panel, the exterior of the liquid crystal display panel is inspected and the failure/pass criteria of the liquid crystal display panel is judged by applying an electrical signal thereto so as to compete the fabrication of the liquid crystal display panel.
Unfortunately, the method of fabricating a liquid crystal display panel according to the related art has the following disadvantages or problems:
First of all, when the automatic sealing operation of the liquid crystal injection inlet experiences some difficulty requiring the worker to seal the liquid crystal injection inlet manually, each of the liquid crystal injection inlets of the liquid crystal display panels must be coated with the sealing material, one-by-one, in creating a plurality of the liquid crystal display panels. The sealing material formed on the liquid crystal injection inlets hardens simultaneously. Eventually, the time required to form the sealing material is extended, whereby the sealing material flows inside the liquid crystal display panel where it is seldom hardened by UV-ray irradiation.
Secondly, since the sealing operation is carried out manually using the syringe type sealing device, the sealing time becomes longer which reduces productivity as well as the result of irregular sealing of the liquid crystal injection inlets of the liquid crystal display panels.
Finally, if the sealing material is excessively formed so as to flow outside the liquid crystal injection inlet, waste of the sealing material is inevitable.